1. you have to watch two hours of streamers with a "twitch drop" addon showing ... it doesn't matter if you own a copy of the game yet and it doesn't have to be two hours in one go but you MUST be signed in as your account while watching for this time to count towards your drop i.e, watching as a guest doesn't help
2 you must have both a Twitch account & a Larian account... Gog Galaxy also assumed here [but not required]
I'm going to assume you have your two hours but are struggling to get your actual reward in game
2 open the Larian Launcher... on the right where it says "MY ACCOUNT" click it then select "ACCOUNT" from the drop down
assume your fiewall isn't protecting you from the big bad internet this should open your default browser... leave the Larian Launcher running [we are coming back ]
3 with your Browser now open to the Larian account page - larian.com - select your account type ... i'm a Gog gamer so I select the Gog icon in this example
that opens another sign in where you actually sign in... note Gog players have the option to NOT link Larian accounts to Gog accounts but its required to get the Twitch drops
4 the next thing is to select connected accounts and you should now see your Gog [/Steam] is showing disconnect... now press the connect buttion under Twitch
depending on browser settings you may get a pop up asking if Larian is allowed to see your Twitch account... say yes
5 leave this page open and go back to the Larian launcher to start your Bg3 game
goto camp [any] open your chest [there could be a few if you already have a couple levels] and sort by 'lastest' to find your new nickers
6 once you find them in game you no longer need the Larian Launcher... i personally don't mind it but some people like to launch the game dirrect from one of the 2 exe
to be clear, you need a twitch account, a Larian account, a Steam or Gog account, they need to all be linked